High strength, high modulus fiber such as Kevlar.RTM. aramid fiber is well-accepted in industry for use in composites of various sorts. Liquid crystal polyester fibers have been known for many years (see U.S. Pat. No. 4,118,372). Heat treated, they too generally exhibit a relatively high tenacity and modulus. For some end-use applications, high modulus is not a requirement and in certain cases, e.g., fishing lines, low modulus fiber is definitely preferred. In some of these applications, greater toughness is the quality sought. The present invention is directed to this need.